Rack::PostBodyContentTypeParser - Adds support for JSON request bodies. The
Rack parameter hash is populated by deserializing the JSON data provided in
the request body when the Content-Type is application/json.

Rack::ProcTitle - Displays request information in process title ($0) for
monitoring/inspection with ps(1).

Rack::Profiler - Uses ruby-prof to measure request time.

Rack::Sendfile - Enables X-Sendfile support for bodies that can be served
from file.

Rack::Signals - Installs signal handlers that are safely processed after
a request

Rack::StaticCache - Modifies the response headers to facilitiate client and proxy caching for
static files that minimizes http requests and improves overall load times for second time visitors.

Rack::TimeZone - Detects the client's timezone using JavaScript and sets
a variable in Rack's environment with the offset from UTC.

Rack::Evil - Lets the rack application return a response to the client from any place.